using System;
using System.Collections.Generic;
using System.Collections.Specialized;
using System.Web;

namespace Kruzya.TelegramBot.RichSiteSummary.UrchinTrackingModule
{
    public class UtmUtility
    {
        public static string ApplyParameters(string url, UtmParameters parameters)
            => ApplyParameters(new Uri(url), parameters);

        public static string ApplyParameters(Uri uri, UtmParameters parameters)
        {
            var query = HttpUtility.ParseQueryString(uri.Query);

            SetIfNotNull(query, "utm_source", parameters.Source);
            SetIfNotNull(query, "utm_medium", parameters.Type);
            SetIfNotNull(query, "utm_campaign", parameters.Campaign);
            SetIfNotNull(query, "utm_term", parameters.Term);
            SetIfNotNull(query, "utm_content", parameters.Content);

            var uriBuilder = new UriBuilder(uri);
            uriBuilder.Query = BuildQueryString(query);
            return uriBuilder.ToString();
        }

        protected static string BuildQueryString(NameValueCollection query)
        {
            var queryParameters = new List<string>();

            foreach (var keyName in query.AllKeys)
            {
                var value = query[keyName];
                queryParameters.Add($"{HttpUtility.UrlEncode(keyName)}={HttpUtility.UrlEncode(value)}");
            }

            return String.Join('&', queryParameters);
        }
        
        protected static void SetIfNotNull(NameValueCollection queryParameteters, string key, string value)
        {
            if (string.IsNullOrWhiteSpace(value))
            {
                return;
            }
            
            queryParameteters.Set(key, value);
        }
    }
}